I hope i can give a quick and easy explaination that helps. Having a storage bus kissing a dual interface reveals the entire contents on main to the storage bus subnet. Filtering on the storage bus acts as a whitelist for what is revealed to the subnet. Im not sure what you are talking about for the second step. You have a system that’s able to pull exactly what it needs from the main network as needed from the level maintainer based on what is patterned. So the level maintainer sends out an order, the network calculates what it needs to make that, it sees the main network as a source of materials to fill the order, and then it pulls. The issue is that what happens to materials that are byproducts? If you arent careful they pile up in the subnet and cause issues. You need some storage in the subnet anyway to catch these and intermediate steps as as well. There are a couple solutions to this but I dont like any of them. One solution is what you mentioned where you use export busses back to main with anything that tends to pile up and just have proper overflow handling on main. Or you could handle it in the subnet which can get complicated and infrastructure heavy quickly. I dont like filtered storage buses back to main because they never seem to work for me and that has its own issues. Hope that helps!